Each object can have different textures as well as different polygons in an object can have different textures (which is a special feature of jPCT when compared to other engines). When you create a 3ds, you usually assign textures to the polygons which are named somehow ("humpel.jpg" for example). When loading this model, the loader asks the TextureManager for textures with these names and assigns them to the polygons. I.e. if your model uses "humpel.jpg" as a texture, you've to load this texture and add it to the TextureManager with the name "humpel.jpg" (the actual file name doesn't matter here) before loading the actual model, so that the 3ds-loader can find it. If it can't find it, it will print out a message that a new default texture (all white) with that name has been created and added to the manager.